Machine-replaceable plasma-facing tile for fusion power reactor environments

ABSTRACT

An apparatus and method are disclosed for machine-replaceable plasma-facing tiles for fusion-power reactor environments. The apparatus and method involve a tile that is fish-scale shaped, and a tile support tube that is attached to the back portion of the tile. The tile support tube includes at least one coolant channel and at least one guard vacuum channel. In one or more embodiments, the method for removing the tile comprises providing a tile that is installed in a manifold channel of a first wall of a fusion power reactor, rotating the tile such that it is in an install/removal orientation, inserting two tines of a removal tool between the outer edges of the tile and the first wall of the fusion power reactor, rotating the removal tool such that the two tines grasp the tile support tube, and lifting the tile away from the wall with the removal tool.

BACKGROUND

The present disclosure relates to tiles for fusion-power reactorenvironments. In particular, it relates to machine-replaceableplasma-facing tiles for fusion-power reactor environments.

SUMMARY

The present disclosure relates to an apparatus, system, and method formachine-replaceable plasma-facing tiles for fusion-power reactorenvironments. In one or more embodiments, the method for installing amachine-replaceable plasma-facing tile for fusion-power reactorenvironments involves providing a tile, where the tile is fish scaleshaped and has a tile support tube attached to the back portion of thetile. The method further involves inserting the tile support tube into amanifold channel of a first wall of a fusion power reactor such that thetile is in an install/remove orientation. Also, the method involvesrotating the tile until the tile is in a locked orientation in themanifold channel of the first wall of the fusion power reactor. In someembodiments, the tile is rotated in a clockwise direction. Inalternative embodiments, the tile is rotated in a counter-clockwisedirection.

In one or more embodiments, the plasma-facing portion of the tile ismanufactured from tungsten (W). In at least one embodiment, the backportion of the tile is manufactured from international thermonuclearexperimental reactor-grade (ITER-grade) stainless steel. In someembodiments, the surface of the back portion of the tile is coated withan electrically insulating material. In at least one embodiment, thetile support tube includes at least one coolant channel. In one or moreembodiments, each coolant channel is manufactured from internationalthermonuclear experimental reactor-grade (ITER-grade) stainless steel.

In one or more embodiments, a method for removing a machine-replaceableplasma-facing tile for fusion-power reactor environments involvesproviding a tile that is installed in a locked orientation in a manifoldchannel of a first wall of a fusion power reactor. The tile isfish-scale shaped, and has a tile support tube attached to the backportion of the tile. The method also involves rotating the tile untilthe tile is in an install/remove orientation. In some embodiments, thetile is rotated in a clockwise direction. In alternative embodiments,the tile is rotated in a counter-clockwise direction.

The method further involves providing a tile removal tool, where thetile removal tool comprises an elongated handle and two tines. One endof each tine is connected to a first end of the handle. Also, a secondend of the handle is located opposite the first end of the handle.Further, the method involves rotating the second end of the handle ofthe removal tool such that the two tines are in an open state.Additionally, the method involves inserting the two tines of the removaltool between the outer edges of the tile and the first wall of thefusion power reactor. Also, the method involves rotating the second endof the handle of the removal tool such that the tines are in a closedstate and grasp the tile support tube. The method further involveslifting the tile away from the first wall of the fusion power reactorwith the removal tool such that the tile is completely removed from themanifold channel of the first wall of the fusion power reactor.

In one or more embodiments, a machine-replaceable plasma-facing tileapparatus for fusion-power reactor environments comprises a tile that isfish-scale shaped, and a tile support tube that is attached to a backportion of the tile. In some embodiments, the tile support tube includesat least one coolant channel and at least one guard vacuum region. In atleast one embodiment, at least one coolant channel is in a verticalorientation. In one or more embodiments, at least one coolant channel isin a horizontal orientation.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is an illustration of the interior of a fusion power reactor, inaccordance with at least one embodiment of the present disclosure.

FIG. 2 shows the overlapping fish-scale arrangement of the tiles thatare installed on the interior wall a fusion power reactor, in accordancewith at least one embodiment of the present disclosure.

FIG. 3 is a depiction of a single machine-replaceable plasma-facing tileapparatus for fusion-power reactor environments, in accordance with atleast one embodiment of the present disclosure.

FIGS. 4A and 4B illustrate the steps for installing amachine-replaceable plasma-facing tile apparatus for fusion-powerreactor environments, in accordance with at least one embodiment of thepresent disclosure.

FIGS. 5A through 5H depict the steps for removing a machine-replaceableplasma-facing tile apparatus for fusion power reactor environments, inaccordance with at least one embodiment of the present disclosure.

FIG. 6 is an illustration of a tile removal tool, in accordance with atleast one embodiment of the present disclosure.

FIG. 7A shows a top view of the tile removal tool in an open state, inaccordance with at least one embodiment of the present disclosure.

FIG. 7B shows a top view of the tile removal tool in a closed state, inaccordance with at least one embodiment of the present disclosure.

FIG. 8A is an illustration of a front view of a tile support tube of amachine-replaceable plasma-facing tile apparatus, in accordance with atleast one embodiment of the present disclosure.

FIG. 8B is an illustration of a side view of a tile support tube of amachine-replaceable plasma-facing tile apparatus, in accordance with atleast one embodiment of the present disclosure.

FIG. 8C is an illustration of a side view of a manifold channel of afirst wall of a fusion power reactor, in accordance with at least oneembodiment of the present disclosure.

FIG. 8D is an illustration of a side view of a tile support tube, of amachine-replaceable plasma-facing tile apparatus, that is installed in amanifold channel of a first wall of a fusion power reactor, inaccordance with at least one embodiment of the present disclosure.

FIG. 9A depicts a top view of a tile support tube of amachine-replaceable plasma-facing tile apparatus, in accordance with atleast one embodiment of the present disclosure.

FIG. 9B shows a bottom view of a tile support tube of amachine-replaceable plasma-facing tile apparatus, in accordance with atleast one embodiment of the present disclosure.

FIG. 10 is a cross-sectional view of the single replaceableplasma-facing tile apparatus for fusion-power reactor environments ofFIG. 3 illustrating that the tile is hollow and thin-walled, inaccordance with at least one embodiment of the present disclosure.

DESCRIPTION

The methods and apparatus disclosed herein provide an operative systemfor tiles for fusion-power reactor environments. Specifically, thissystem allows for machine-replaceable plasma-facing tiles forfusion-power reactor environments. The system of the present disclosureteaches an easily machine-replaceable high heat and radiationflux-tolerant tile for lining the inner wall of a fusion reactor thatproduces power-plant levels of heat and radiation flux. The tile of thepresent system protects the underlying structures of the reactor fromdamage by plasma impact as well as from tritium and alpha particleinfiltration from a fusing deuterium (²H)-tritium (³H) nuclear reactionin magnetically confined plasma.

Projections from current experiments indicate that the plasma in afusion power reactor will be sufficiently energetic such that in awell-controlled reactor, it will be capable of destroying the innermostlayer of the plasma chamber in a matter of weeks to months. Currently,there is no known economically acceptable way to replace the interior ofthe reactor every few months.

There are three ways to mitigate this problem. The first way is tobetter control the plasma such there are fewer plasma impacts on thefirst interior wall of the reactor. The second way is to manufacture thefirst interior wall of the reactor from materials that are able totolerate many plasma impacts. And, the third way is to manufacture thefirst interior wall such that it is easy and cheap to replace, and suchthat it protects the other wall layers that lie behind it. In addition,projections from current experiments and the state of the art intechnologies for control and materials also indicate that all threeapproaches will be required for a viable fusion reactor. The system ofthe present disclosure addresses the third approach.

Another problem realized from current experiments is that, in reactorconditions, most known materials become somewhat permeable to tritium(³H), which is the radioactive component of the fuel of the reactor.This permeability allows the materials that line the reactor chamber toabsorb some tritium. As such, the materials become slightly radioactivethemselves. This causes some tritium to pass through the materials,thereby causing some of the radioactive tritium fuel to leak away. Thesystem of the present disclosure also addresses the tritium permeabilityproblem.

Currently, there are several proposed solutions to address theseabove-discussed problems. The first proposed solution is to build plasmacontrol systems that are able to reduce plasma impacts from several perminute to several per month. The second proposed solution is to find amaterial that is able to tolerate multiple plasma impacts per minute inthe high heat and radiation flux environment of a fusion power reactorwithout suffering significant erosion, embrittlement, and absorption oftritium. The third proposed solution is to replace the multi-ton firstwall/breeding blanket structures lining the interior of the fusion powerreactor every few months. However, it should be noted that none of theabove-mentioned proposed solutions have yet been developed beyond theconcept stage, let alone demonstrated.

Also, there are several notable disadvantages to these three proposedsolutions. The first disadvantage is that control systems have not beenbuilt that are able to reduce plasma impacts from several per minute toone per month, and may never be possible. The second disadvantage isthat models and experiments indicate that there is no known materialthat will survive more than ten fusion power reactor-level plasmaimpacts near the same spot without suffering significant materialerosion. And, the third disadvantage is that replacing the multi-tonfirst wall/breeding blanket structures lining the interior of the fusionpower reactors will be so difficult and expensive that it will beimpractical to replace these structures at any rate exceeding once everythree years.

Several constraints must be solved simultaneously for the first interiorwall of a fusion power reactor. These constraints are as follows. Thefirst constraint is that the energy flux through the first wall, whichis in the form of neutrons, gammas, and alpha particles, will exceed 1megawatt per square meter (MW/m²). The second constraint is that, forefficient thermodynamics of the power reactor and for the effective useof the reactor for the production of hydrogen, the first wall (andbreeding blanket), coolant outlet temperature should be at least 700degrees Celsius (C), and preferably will be 950 degrees C. The thirdconstraint is that neutrons from the reaction are energetic enough tobreak any molecular bond and knock metal atoms out of their originalpositions in the metal lattice.

The fourth constraint is that the first wall must not release vaporsinto the vacuum surrounding the plasma. The fifth constraint is that thefirst wall must be manufactured from materials that have a minimalpropensity for neutron activation. The sixth constraint is related tothe fact that some alpha particles from the reaction will enter thefirst wall and become trapped. There, the alpha particles will pick upelectrons, thereby becoming neutral helium atoms. Eventually enoughatoms will accumulate to form bubbles in the material of the wall. Assuch, the first wall must tolerate or neutralize these bubbles.

The seventh constraint is related to the fact that tritium from the fuelwill enter the first wall material, thereby making the material bothbrittle and slightly radioactive. Thus, the first wall must have a wayto mitigate the brittleness and remove the tritium. The eighthconstraint is that the first wall must be able to tolerate plasmaimpacts or be easily replaceable after damage from impacts, but beforeaccumulated damage breaches the first wall. The ninth constraint is thatthe first wall must be very thin such that it does not interfere withthe transit of neutrons from the reaction through the first wall andinto the breeding blanket located behind the first wall.

The tenth constraint is that the first wall must be repairable orreplaceable by machine. Despite the intent to build fusion reactors frommaterials that are not prone to neutron activation, an activation willoccur. This means that the reactor will become radioactive itself to alevel such that it will not be approachable by human maintainers untilafter being off for approximately one month. And, the eleventhconstraint is that the elements of the first wall must be recyclableafter only a short cooling period, even if the recycling only consistsof the elements being made into new tiles for fusion reactors. Thesystem of the present disclosure addresses the above constraints in avariety of ways. These various ways are discussed in detail below.

In the following description, numerous details are set forth in order toprovide a more thorough description of the system. It will be apparent,however, to one skilled in the art, that the disclosed system may bepracticed without these specific details. In the other instances, wellknown features have not been described in detail so as not tounnecessarily obscure the system.

FIG. 1 is an illustration of the interior of a fusion power reactor 100,in accordance with at least one embodiment of the present disclosure. Inthis figure, it can be seen that the fusion power reactor 100 is of atorus shape. It should be noted that the system of the presentdisclosure can be used with various different types and shapes of fusionpower reactors. The first wall of the fusion power reactor 100 is linedwith small tile apparatus units 110.

Each small tile apparatus unit 110 is individually replaceable. Tileinstallation and removal is performed by a remote robotic maintenancesystem that enters the plasma chamber through an access port. An exampleof a remote robotic maintenance system is the MASCOT remote maintenancedevice that used for the Joint European Torus fusion energy experiment.It should be noted that various other types of remote roboticmaintenance systems may be used for the system of the presentdisclosure. The remote robotic maintenance system will need only simpletools, such as those shown in FIG. 6 to install and remove the tileapparatus units 110.

The tile apparatus units 110 that line the first wall of the fusionpower reactor 100 overlap each other in a fish-scale pattern. FIG. 2shows the overlapping fish scale arrangement of the tile apparatus units110 that are installed on the interior wall of a fusion power reactor,in accordance with at least one embodiment of the present disclosure.

FIG. 3 is a depiction of a single machine-replaceable plasma-facing tileapparatus 110 for fusion-power reactor environments, in accordance withat least one embodiment of the present disclosure. Eachmachine-replaceable plasma-facing tile apparatus 110 comprises a tile300 that is fish-scale shaped, and a tile support tube 310. The tilesupport tube 310 is attached to the back portion of the tile 300. In oneor more embodiments, the tile support tube 310 includes at least onecoolant channel (not shown in figure) and/or at least one guard vacuumregion (not shown in figure).

FIGS. 4A and 4B illustrate the steps for installing amachine-replaceable plasma-facing tile apparatus 110 for fusion-powerreactor environments, in accordance with at least one embodiment of thepresent disclosure. For FIGS. 4A and 4B, the spot on the tile 300 of thetile apparatus 110 indicates the axis on which the tile apparatus 110rotates. And, the circle on the tile 300 indicates the location of thetile support tube 310 (not shown in figure), which is attached to theback portion of the tile 300 of the tile apparatus 110.

For the first step, which is shown in FIG. 4A, the tile apparatus 110has its tile support tube 310 (not shown in figure) inserted into amanifold channel of a first wall of a fusion power reactor such that thetile apparatus 110 is in an install/remove orientation. For the secondstep, which is shown in FIG. 4B, the tile apparatus 110 is rotated untilit is in a locked orientation in the manifold channel of the first wallof the fusion power reactor. In one or more embodiments, for the secondstep, the tile apparatus 110 is rotated in a clockwise direction. Inalternative embodiments, for the second step, the tile apparatus 110 isrotated in a counter-clockwise direction.

FIGS. 5A through 5H depict the steps for removing a machine-replaceableplasma-facing tile apparatus 110 for fusion power reactor environments,in accordance with at least one embodiment of the present disclosure.For FIGS. 5A through 5H, the spot on the tile 300 of the tile apparatus110 indicates the axis on which the tile apparatus 110 rotates. And, thecircle on the tile 300 indicates the location of the tile support tube310 (not shown in figure), which is attached to the back portion of thetile 300 of the tile apparatus 110.

For the first step, which is shown in FIG. 5A, a tile apparatus 110 isinstalled in a locked orientation in a manifold channel of a first wallof a fusion power reactor. For the second step, which is shown in FIGS.5B through 5E, the tile apparatus 110 is rotated until the tileapparatus 110 is in the install/remove orientation. In one or moreembodiments, for the second step, the tile apparatus 110 is rotated in acounter-clockwise direction. In alternative embodiments, for the secondstep, the tile apparatus 110 is rotated in a clockwise direction.

A tile removal tool 500 is used for the third step of the installationprocedure. FIG. 6 shows an illustration of a tile removal tool 500, inaccordance with at least one embodiment of the present disclosure. Thetile removal tool 500 comprises an elongated handle 600 and two tines610. One end of each tine 610 is connected to a first end 620 of thehandle 600. A second end 630 of the handle is located opposite the firstend 620 of the handle 600.

For the third step, the second end 630 of the handle 600 of the tileremoval tool 500 is rotated such that the two tines 610 are in an openstate. In one or more embodiments, the second end 630 of the handle 600of the tile removal tool 500 is rotated in a clockwise direction inorder to orient the two tines 610 in an open state. In alternativeembodiments, the second end 630 of the handle 600 of the tile removaltool 500 is rotated in a counter-clockwise direction in order to orientthe two tines 610 in an open state. FIG. 7A shows a top view of the tileremoval tool 500 in an open state, in accordance with at least oneembodiment of the present disclosure. For the fourth step, which isshown in FIG. 5F, the two tines 610 of the tile removal tool 500 areinserted between the outer edges of the tile 300 and the first wall ofthe fusion power reactor.

For the fifth step, which is shown in FIG. 5G, the second end 630 of thehandle 600 of the tile removal tool 500 is rotated such that the twotines 610 are in a closed state and grasp the tile support tube 310 (notshown in figure). In one or more embodiments, the second end 630 of thehandle 600 of the tile removal tool 500 is rotated in acounter-clockwise direction in order to orient the two tines 610 in aclosed state. In alternative embodiments, the second end 630 of thehandle 600 of the tile removal tool 500 is rotated in a clockwisedirection in order to orient the two tines 610 in a closed state. FIG.7B shows a top view of the tile removal tool 500 in a closed state, inaccordance with at least one embodiment of the present disclosure. Forthe sixth step, which is shown in FIG. 5H, the tile apparatus 110 hasbeen lifted away from the first wall of the fusion power reactor withthe removal tool such that the tile apparatus 110 is completely removedfrom the manifold channel of the first wall of the fusion power reactor.

For the system of the present disclosure, it should be noted that thetiles 300 are not intended to seat tightly against each other. Theirpurpose is to be a sacrificial first wall that is easily replaceable,and protects the structures that lie behind it. The tiles 300 willoverlap, and should touch, but only if the outermost surface of the backsides of the tiles 300 are electrically insulating. Because if the tilestouch and can conduct electric currents from one tile 300 to another,there is too great a chance of the tiles 300 being welded to each otherby plasma disruptions, which would make replacement of damaged tileapparatus units 110 difficult. The reason the tiles 300 should touch isso that they can provide some mechanical support to each other to helpthem resist the electromagnetic forces that are generated during plasmadisruptions. However, the tiles 300 must not lock or seal to each otheras electromagnetic forces could damage an interlocking system in waysthat could prevent it from being unlocked.

Because the tiles 300 are not sealed against each other, the tileapparatus units 110 need to have a portion of their interior channelsemployed by a vacuum pumping system, which is located behind the tiles300. This will serve several purposes. First, it will prevent thebuild-up of gases behind the tiles 300. Second, it will prevent any gasthat is leaking from the tile attachment system from getting into theplasma. And third, it will allow the size of the main vacuum pumpingports to be reduced.

In one or more embodiments, the tile apparatus units 110 are madeentirely of refractory materials. This feature will prevent the tileapparatus units 110 from releasing vapors into the vacuum. Therefractory materials to be used for the tile apparatus units 110 havelow neutron activation cross sections and are able to resist plasmaimpacts. These features will facilitate the recycling of the tileapparatus units 110. Examples of materials to be used for the tileapparatus units 110 include, but are not limited to, tungsten (W) forthe plasma-facing portions of the tiles 300, and internationalthermonuclear experimental reactor-grade (ITER-grade), low activation,stainless steel for the back portions of the tiles 300, the tile coolantchannels, and the tile support tubes 310. In some embodiments, theoutermost surface of the back portion of each tile 300 is coated with anelectrically insulating material, such as silicon carbide (SiC) ortungsten carbide (WC).

In one or more embodiments, the tiles 300 are hollow and thin-walled,and have a cooling fluid, such as helium (He), that possibly contains atracer consisting of another noble gas (e.g., argon (Ar)), flowingthrough them. The thin walls of the tiles 300 allow neutrons to passlargely unimpeded through the tiles 300 into the breeding blanket.Because of their charge, tritons (tritium nuclei) do not pass throughmetals as easily as neutrons. Tritons escaping from the plasma willmostly be stopped on or in the tile 300 walls, where they will beneutralized. Once neutralized, the tritium atoms have some ability tomigrate through metals. The thin walls of the tiles 300 will allowtritium entering into the tiles to migrate easily through the walls intothe helium coolant, which will carry them away for chemical capture.

The fusion reactions will also produce alpha particles, most of whichwill stop in the tile 300 walls like the tritons. As with the tritium,the thin tile 300 walls will allow helium forming from the alphaparticles to diffuse easily to the coolant channel for removal with onlyminimal damage to the walls themselves, because the distance the heliummust migrate will be very short. The coolant will enter and leave thetiles 300 through tubes that project radially outward from the tiles 300(i.e., the coolant channels in the tile support tubes 310) through thebreeding blankets to connections to the helium supply and the returnmanifolds, which could be located inside or beyond the breedingblankets.

Because the tile apparatus units 110 are rotated during the installationand removal process, a very simple method is possible for attaching thetile apparatus units 110 and making the coolant connections. Theattachment and connection methods must be simple to minimize thepossibility that electromagnetic forces occurring during a disruptionwill distort the tile 300 and tile support tube 310 so greatly that thetile apparatus unit 110 cannot be easily removed.

There are several ways the attachment can be accomplished. But thesimplest, which is the preferred embodiment, is to have the tile supporttubes 310 manufactured to have one or more sets of offset semi-circularshoulders and to have similar semi-circular shoulders located on theinside of the manifold channels into which the tile support tubes 310are inserted. By rotating the tile apparatus units 110 multiple timesduring installation, or by rotating the tile apparatus units 110multiple times back and forth by half circles, the offset shoulders oneach tile support tube 310 can be made to clear the offset shoulders ineach manifold channel until the tile support tube 310 is fully inserted.

FIGS. 8A through 8D show an example of a way to manufacture the offsetshoulders on a tile support tube 310 that attaches to a manifold channel820 in the breeding blanket. In the event that the coolant manifold islocated beyond the breeding blanket, rather than being in it, the tilesupport tubes 310 will be manufactured to be much longer in length, andthey will each have at least two sets of shoulders. The set of shoulderslocated closest to the plasma will be only for mechanical support. And,a second set of shoulders will be located farther from the plasma, wherethey can engage the coolant passages in a manifold beyond the blanket.

FIGS. 8A through 8D also show an example of a way that inlet and outletcoolant connections can be made between the coolant channels 800 of atile support tube 310 and the coolant channels 810 in a manifold channel820. These figures show the routing of coolant channels 800 in a tilesupport tube 310 such that they come to the inboard faces of theshoulders on the tile support tube 310, and mate to correspondingcoolant channels 810 located on the outboard faces of the shoulders inthe manifold channel 820. The simplest way to make these connections isto start by manufacturing the tile support tubes 310 and the walls ofthe manifold channels 820 of the same material, such as ITER-gradestainless steel. That will minimize problems from differential thermalexpansion of various parts, and will allow for the use of simplemetallic, such as copper (Cu), seals between the faying steel surfaces.

In addition, FIGS. 8A through 8D show a simple way to make the sealbetween the shoulders of the tile support tube 310 and the shoulders ofthe manifold channel 820, which is to simply have a spring 850 attachedto the end of the tile support tube 310, which pushes the shoulders upagainst each other. In one or more embodiments, the spring 850 is acaptive spring such that it can be easily replaced if thermal cycling orradiation damages it.

It should be noted that because of the intense radiation environment,the seals cannot be made from elastomeric materials, and are metal.Because the seals are simple, there is a possibility of an occurrence ofunacceptable leakage of radiation. Possible leakage is prevented frombeing a problem by the use of a standard vacuum system technology, suchas a guard vacuum. A guard vacuum is simply a separate volume that islocated between two volumes having different pressures. The guard vacuumusually has a pressure that is between the pressures of the two volumesbeing separated. A guard vacuum reduces leakage through vacuum seals byreducing the pressure difference across each seal. Simply adding twoseals might appear to accomplish the same thing. However, if two sealsare implemented, the space between them traps gas, which leaks out veryslowly, and is called a “virtual leak”. The creation of a guard vacuumeliminates the risk of creating a virtual leak between the two seals.FIGS. 9A and 9B show in detail views from above and below of the coolantconnection system.

FIG. 9A depicts a top view of a tile support tube 310 of amachine-replaceable plasma-facing tile apparatus and FIG. 9B shows abottom view of a tile support tube 310 of a machine-replaceableplasma-facing tile apparatus, in accordance with at least one embodimentof the present disclosure. In FIG. 9A, it can be seen that the tilesupport tube 310 contains a tube support body 900, two vertical coolantchannels 910, four horizontal coolant channels 920, two guard vacuumregions 930, two first vacuum seals 940, two second vacuum seals 950,two tube shoulders 970, and two coolant passages 960 in the tubeshoulders 970. From FIG. 9B, it can be seen that the tile support tubecontains a tube support body 900, two guard vacuum regions 930, twofirst vacuum seals 940, two second vacuum seals 950, two tube shoulders970, and two coolant passages 960 in the tube shoulders 970.

Variations on the attachment system can be developed in the event thatthe disclosed simple approach does not hold the tile support tubes 310firmly enough, or if the coolant seals require more normal force to workproperly. For example, tile support tubes 310 could be made of copper(Cu), while the manifold channels 820 that they are set into are formedfrom ITER-Grade stainless steel. Copper is acceptable in the fusionenvironment, as long as copper alloys containing high-neutron activationelements, such as nickel (Ni), are avoided. If copper is used for thetile support tube 310, and a lower set of mechanical stops is put in themanifold channel 820 in addition to the spring 850, then when the systemheats during operation, the copper will expand more than the stainlesssteel. That will cause the distance between the stop and the coolantconnection shoulders on the tile support tube 310 to grow more than thedistance between the stop and the coolant connection shoulders in themanifold channel 820. The effect of that will be that, as the deviceheats, the force will grow with which the faying surfaces and the sealfor the coolant connections are pushed together.

FIG. 10 is a cross-sectional view of the single replaceableplasma-facing tile apparatus 110 for fusion-power reactor environmentsof FIG. 3 illustrating the tile 300 that is hollow 1000 and thin-walled1010, in accordance with at least one embodiment of the presentdisclosure.

Although certain illustrative embodiments and methods have beendisclosed herein, it can be apparent from the foregoing disclosure tothose skilled in the art that variations and modifications of suchembodiments and methods can be made without departing from the truespirit and scope of the art disclosed. Many other examples of the artdisclosed exist, each differing from others in matters of detail only.Accordingly, it is intended that the art disclosed shall be limited onlyto the extent required by the appended claims and the rules andprinciples of applicable law.

I claim:
 1. A method for installing a replaceable plasma-facing tile forfusion power reactor environments, the method comprising: inserting atile support tube of the replaceable plasma-facing tile into a manifoldchannel of a first wall of the fusion power reactor such that the tileis in an install/remove orientation, wherein the tile support tube isattached to a back portion of the tile and the tile support tubecomprises at least one coolant channel and wherein the tile support tubeis configured to provide direct contact between coolant from the atleast one coolant channel and the back portion of the tile, and whereinthe at least one coolant channel is perpendicular to the back portion ofthe tile; and rotating the tile until the tile is in a lockedorientation in the manifold channel of the first wall of the fusionpower reactor.
 2. The method for installing a replaceable plasma-facingtile for fusion power reactor environments of claim 1, wherein the tileis rotated in a clockwise direction.
 3. The method for installing amachine-replaceable plasma-facing tile for fusion power reactorenvironments of claim 1, wherein the tile is rotated in acounter-clockwise direction.
 4. The method for installing a replaceableplasma-facing tile for fusion power reactor environments of claim 1,wherein a plasma-facing portion of the tile is manufactured fromtungsten (W).
 5. The method for installing a replaceable plasma-facingtile for fusion power reactor environments of claim 1, wherein the backportion of the tile is manufactured from international thermonuclearexperimental reactor-grade (ITER-grade) stainless steel.
 6. The methodfor installing a replaceable plasma-facing tile for fusion power reactorenvironments of claim 1, wherein a surface of the back portion of thetile is coated with an electrically insulating material.
 7. The methodfor installing a replaceable plasma-facing tile for fusion power reactorenvironments of claim 1, wherein the at least one coolant channel ismanufactured from international thermonuclear experimental reactor-grade(ITER-grade) stainless steel.